With the development of electronic technology, various display devices have been developed. Display devices, such as CRT, LCD, PDP and OLED, which include various display parts, have been used.
However, the existing display devices have a limitation in that users have no option but to view contents in one direction where a display unit is arranged.
In order to solve such a limitation, studies of a transparent display device have been ongoing.
The transparent display device has an advantage in that a user may view contents displayed on a display unit together with a subject on a rear surface of the display unit as the display unit is transparent.
Also, the transparent display device has an advantage in that a third party located at an opposite side of the user may view contents displayed on the display unit together with the user.
However, as studies of the transparent display device have been focused on development of hardware, studies on how to use the transparent display device and studies of contents development are not sufficient.
Therefore, development of a transparent display device has been required, which is attached to a predetermined product to serve as a door unit and at the same time may display various functions such as article information in the product and advertisement.